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# VARLSPUMP: variable displacement pump (LS control) - how to set it up?

Hi All,

Does anyone know how to set up

VARLSPUMP: variable displacement pump (LS control)

that is used in the Wheel Loader demo?

I know how to change the pump displacement .

I would like to change the drop off characteristic i.e the pressure vs flow characteristic. Currently the pump flow is max up to 105bar and then decreases . I would like the pump flow to start decreasing at 72bar.

Many thanks.

Regards

Dariusz

Solution
Solution
Accepted by topic author DariuszP
‎04-03-2017 05:25 AM

## Re: VARLSPUMP: variable displacement pump (LS control) - how to set it up?

Hi DariuszP

The targeted maximal delivery pressure is a combination of the cracking pressure of the check-valve CV002 (acting as a relief valve on LS line) and the spring force in the submodel BAP016 in charge of setting the load sensing differential pressure.

Those two submodels being at the bottom right of the supercomponent VARLSPUMP:

The LS pressure differential setting is obtained thanks to the spring in BAP016, with the demo parameters it is near 31 bars, the cracking pressure of the checkvalve is 250 bar (really high, in fact it is never reached in the demo scenario, the checkvalve never opens), thus the maximum controlled pressure is about 250+31 = 281 bar.

If you reduce the check-valve cracking pressure to 100 bar, the maximum controlled pressure is about 131 bars and this effect can now be seen during some sequences of the demo scenario (it's easier to see it on an elementary system):

Maybe you would be interested by the submodels developed for Amesim 1500 specifically for pump controls.

You can find some info about them in Amesim documentation & What's New:

They describe the control in a more functional manner than HCD which requires a good knowledge of the geometry of the valves. They are not fully similar to VARLSPUMP supercomponent which integrates a discharge of the LS line but they should be fine to model most of the common control strategies.

You can also be interested by some others developments done in 1500, like pumps with external drain and some elementary hydraulic control valves previously missing (still in AmeHelp/What's New rev15 see Hydraulic section).

In any case, don't hesitate to contact the support team if you miss some info or functionality.

Best regards,

Yohan